How the blink affects contact lens wear

December 10, 2019

Behold the significant, protective power of the eyelids

Have you ever sat across from a patient in the exam chair and become distracted by his partial blinks? So much so that you couldn’t hear his talking? What is even more awkward is when you see this with your waitress or banker-or the potential staff member you are interviewing. I find myself biting my tongue to keep from going into a functional anatomy lesson or worse yet, just blurt out, “Will you blink already?!”
If an eye stayed closed, it would never dry. This thought helps us to understand the significant protective power of the eyelids. Occasionally, a patient will realize that she doesn’t sleep with her eyes fully closed, but rarely do patients realize they could be blinking incorrectly.
Consequences of a poor blink
A proper blink cleanses, moisturizes the ocular surface and replenishes the nutrients, oil and water supply in the tear film.
When lids do not make contact during a blink, there are negative consequences.
A lack of lid-to-lid contact causes meibomian glands not to release meibum. These glands can eventually clog and atrophy over time. Evaporative stress causes more inflammation which can then cause further degradation of the meibomian glands, leading to more evaporative stress and exposure. 

Related: How to succeed with multifocal contact lenses
Improper blinking causes a pumping action of the lacrimal gland and drives tears down the canaliculi-as a means of cleansing the ocular surface. The most obvious detriment of this is the corneal and conjunctival exposure that occurs, which can lead to surface cell degradation and progressive consequences to the vision and comfort.
How does a blink change with contact lens wear?
With every contact lens exam, I acquire an interferometry video, tear film dynamic video, and a redness assessment. This tells me if there is an incomplete blink pattern, undue exposure of the lens, and how much the contact lensdries as a result, as well as build up on the lens. It is also a great education tool. It helps demonstrate the fit and movement of the lens as well.
A few years ago, we had a LipiView (Johnson & Johnson Vision) in our office. Driven by nothing other than curiosity, we decided to conduct a simple internal review on how contact lens wear might impact the blink. We found that in each of the several patients tested with and without their contact lenses, the trend was the same. The overall number of blinks decreased, and the number of incomplete blinks increased with contact lenses.

Related: How to master hybrid contact lenses
Resultantly, this increased the patients’ lipid layer thickness as much as 70 percent in some. It is not clear how thick a patient’s lipid layer needs to be and what degree of increase reduces symptoms. My most extreme patients come to mind, who had no remaining glands and were stuck with discomfort, even with treatment. Perhaps any improvement we can make in our contact lens patients, through education and limiting contact lens wear time, will help preserve glands.
We know a patient’s blink rate decreases when staring at a device. Patel et al1 showed it decreases from a mean of 18.4 blinks per minute (bpm) to 3.6 bpm during device use, and Tsubota and Nakamori2 showed a mean decrease from 22 bpm to 7 bpm. Now ODs are finding meibomian gland loss in kids and adolescents and blaming screen time for premature loss.
Additional thoughts to keep in mind:
A recent study by Jie et al3 validated the assumptions that partial blinking is directly correlated to decreased tear film break-up time (TBUT) and both increased meibomian gland disease (MGD) and Ocular Surface Disease Index (OSDI) scores.
Garcia-Montero et al correlated a decrease in the optical quality dynamics of the tear film among contact lens wearers with the lowest blink rates. This correlation was consistent among all four of the contact lens brands being tested.4
Anecdotally, we know that the blink is affected by contact lens wear, and the contact lens wearer is often the same person who sits in front of the computer for eight to 12 hours per day.
When 426 subjects were assessed, contact lens wearers logging at least six hours of computer use had a higher prevalence of dry eye disease versus non-wearers with the same amount of device use.5

Related: Review clinical highlights of new myopia control lensWhat to do about it
Public education seems to be the best strategy. We are already seeing examples of this being put into place. Every Sunday my iPhone tells me my average daily hours of screen time for the week. I can envision prime-time commercials and device labels with warnings one day…far away.
I love showing patients a slow-motion video of their blinks with fluorescein and a cobalt blue filter. When there is complete closure the entire screen goes black, which makes it quite easy and obvious to see when the lids don’t close completely. After the show and tell, I demonstrate the blink exercise and stress the importance of creating muscle memory and a new habit. Frequently, patients return saying they have now repeatedly caught themselves not blinking-and that it happens more than they could have fathomed.
But what if we could take it one step further? What if there was wearable technology that notified the patient when she was not blinking completely? Or if she was informed when there was significant tear film debris or build up on their contact lenses? 
I am a firm believer that anything measured is improved. When my wrist buzzes at the 10,000-step mark on my Fitbit, there is a joyful release of dopamine for a job well done. Imagine how this concept could influence ocular outcomes, both immediate and long term.

More by Dr. Brimer: Why ODs shouldn’t stop short with patient care

References:

1. Patel S, Henderson R, Bradley L, Galloway B, Hunter L. Effect of visual display unit use on blink rate and tear stability. Optom Vis Sci. 1991 Nov;68(11):888-92.
2. Tsubota K, Nakamori K. Dry eyes and video display terminals. N Engl J Med. 1993 Feb 25;328(8):584.
3. Jie Y, Sella R, Feng J, Gomez ML, Afshari NA. Evaluation of incomplete blinking as a measurement of dry eye disease. Ocul Surf. 2019 Jul;17(3):440-446.
4. García-Montero M, Rico-Del-Viejo L, Martínez-Alberquilla I, Hernández-Verdejo JL, Lorente-Velázquez A, Madrid-Costa D. Effects of Blink Rate on Tear Film Optical Quality Dynamics with Different Soft Contact Lenses. J Ophthalmol. 2019 Jul 9;2019:4921538.
5. Sheppard AL, Wolffsohn JS. Digital eye strain: prevalence, measurement and amelioration. BMJ Open Ophthalmol. 2018 Apr 16;3(1):e000146.